Automatic train-control system



E. C. SASNETT AUTOMATIC; TRAIN CONTROL SYSTEM Flled Aug '7, 1925 l i R Nov. 6, 1928. 1,690,505

E. c. SASNETT AUTOMAT IC TRAIN CONTROL SYSTEM Filed Aug. 1925 3 Sheets-Sheet 2 R v i 3 Sheets-Sheet 3 Jnvwnioo E. C. SASNETT AUTOMATIC TRAIN CONTROL SYSTEM Filed Aug. '7, 1925 Nov. 6, 1928.

Patented Nov. 6, 1928.

UNITED STATES EDWARD C. SASNETT, OF WASHINGTON, DISTRICT OF COLUMBIA.

AUTOMATIC TRAIN-CONTROL SYSTEM.

Application filed August 7, 1925. Serial No. 48,746.

The present invention relates to automatic train control systems of the continuous indi c: tion type.

The invention has for its object to provide a system in which the various indications are controlled by codes of electrical impulses transmitted from the; track in any suitable manner, the indications varying in accordance with the particular code transmitted.

"lhe acompanying drawings illustrate several substantially different embodin'ients of the invention.

Fig. 1 is a diagrammatic view of a system cn'iploying synchronized track circuit controllers; Figs. 2 and 3 are diagrammatic views of systems employing non-syncl'ironized controllers; and Figs. 1 and 1 are detail views of certain elements of the system shown in Fig. 1.

Referring first to the system shown by Fig. 1. conducted across the rails of a conductively continuous stretch of track at regularly spaced stations A, B, C and D are conductors 11 and 12 leading respectively to the termi mile of transformers 13, the prin'iaries of these transformers being connected across alternating current power mains M. A switch l i is inserted in the conductor 11 and is adapted to be periodically operated by mechanism hereinafter described so as to impress the voltages of the secondaries across the track rails at certain intervals.

There is provided at each station a single phase motor 15 fed from the secondary of the respective transformer. Rigid with the armature of each of these motors is a worm shaft 16 meshing with a worm wheel 17 secured on a shaft 18. a sleeve 19 rigid with which is a gear 20 fric tionally engaged by a disk 21 splined on shaft 18, a spring effecting a suitable pressure between the disks, see Fig. 1. Secured to sleeve 19 is a cam 23 having raised portions adapted to operate circuit controllers 14:.

Meshing with gear 20 is a gear 241 rigid with a shaft, and also rigid with said shaft is a Z-shaped armature 2G and an arm 27. Armature 26 has curved pole faces coacting with concave pole faces of magnets 28. Arm 2'?" is adapt d to close circuit controller 29 for an instant at accrtain point in each revolution of shaft T he diameter of gear 24: is e actly twice that of gear 20, so that cam 80 will always occupy a certain position when the armature 26 lies in the magnetic axis of magnets 28.

Rotatable on shaft 18 is' It will be observed that when arm 27 closes switch 29 at any given station, the circuit of magnet 28 at the station immediately in rear is closed. If the raised portions of camsl 23 at the two stations are in correct relative positions, armature 26 at the rear station will lie in the magnetic axis of magnets 28 when switch 29 at the advance station is closed. If the raised portions are not in correct relative positions, armature 26 at the rear station will be drawn into the magnetic axis, rotating the cam at the rear station, this adjustment being permitted by the frictional connection of the cam with the driving shaft 18. i

Each cam 23 comprises a long raised portion 80 extending through an arc of about 180 and having the same angular position at all of the stations, and a short raised portion 81, which at any given instant occupies a different angular position at stations in the same group. The stations are arranged in groups of three. Stations A, B and C constitute one group, and station D is the first of the group of three next in advance. At stations A and D the projections 81 have the same angular position, and this is true of these projections at stations B and E (not shown) and at stations G and F (not shown). That is to say, the projections 81 have dif ferent angular positions at stations of the same group but have the same angular positions at corresponding stations of the several groups. With this disposition it will be obvious that a vehicle under clear conditions (three blocks ahead clear) will receive three short current impulses followed by along impulse, at regularly recurring intervals. With only two blocks ahead clear (caution conditions) the vehicle will receive two current impulses followed by a long impulse, and under danger conditions (one block ahead clear) it will receive one short current impulse followed by a long impulse.

The vehicle equipment includes a coil 30 disposed in inductive relation to the track rails, an electro-magnetic relay 31 and an amplifier between the coil and relay. Relay 31.

controls the operation of impulse mechanism including a ratchet wheel 85, a driving pawl 86 and a holding pawl 87. The driving pawl I is operated by a magnet 88 and the holding pawl bya magnet 89. These magnets are connected in series so as to be energized when re lay 31 is energized by means of the following circuit: battery B, conductor 90, front contact 91, conductor 92, magnets 89 and 88, conductor 93 and back to battery through-front contact 9 1. Pawl 86 is adapted to be operated by magnet 88 to step wheel 85 through an angle I by a long impulse. operate to step wheel 85 through anangle of of one tooth upon the reception of each short impulse and of course to stepgit through the same angle at the beginning of the long impulse, but pawl 87 is not operated torelea'sewheel 85 until energized a predetermined time upon reception otthelong impulse. Any sultablemoans for retard ng the action of pawl 87 may be used. The means illustrated consists of a dash pot 95 having a stem 96"- on its plunger abuttingthe backside of pawl 81 the parts being constructed to'retard the release movement suiiicien'tly to prevent release of wheel 85when short impulses are being' received. i 8 f Rigid with wheel 85 is a disk 96 havingon its periphery three projections 97, 98 and'99 (Fig. 2); [These projections arecir'culnferentially and axially displace-d with respect to each other and are adapted respectively to operate circuit controllers 100, 101 and 102. 25,

When the wheel is stepped through two teeth,

projection 97 closes controller 100; when.

steppedithrough three teeth, projection 98 closes controller 101; and when stepped through four teeth, projection 99 closes controller 102. These circuit controllers control magnets 103, 10 and 105, respectively, and these magnets in turn control a green lamp 106, ayellow lamp 107 and a red lamp 108.

As above pointed out, under clear conditions the vehiclereceives at regularly recurring'intervals three'short impulses followed The threeshort impulses three teeth and then at the beginningof the long impulse the wheel is stepped through an additional tooth and shortly thereafter the holding pawl is withdrawn from wheel 85 and" the latter resumes initial position being biased to such positionby aspring, as indicatedon the drawlng, and being stopped'at such position by a suitable stop, not shown. An instant before wheel 85 is released the following ClICUli) is closed :battery B, front contact 94;,conduc tor 93, conductor 109, contacts 110 (closed by pawl 87 in advance of the release of wheel 85) conductor 111, contacts 102, conductor 112,

magnet 103, andback to battery through conductor 113. Thus under clear conditions, magnet 103is intermittently energized, operating to maintain the circuitof green lamp 106 closed. The interval separating the impulses through magnet 103 will depend of course upon the angular velocity of cams 28,

and this may be of any value desired. If for example these cams make one revolution every four seconds, magnet 103 will receive an impulse every four seconds, under clear conditions.

Under caution conditions, the vehicle will ,reeeivetwo short impulses followed by a long impulse. Accordingly in each cycle of operations wheel will be stepped through three steps and then released. W hen the wheel is stepped through three steps the contactsot controller 101' are closed and therefore just prior totlie release of the wheel the following circuitis closed: battery B, front contact 94, conductors 93 and 109, contacts110, conductor 111, circuit controller 101, conductor 1'14, magnet 10 1 and back to battery through conductor 113. Hence under caution conditions magnet 10 1 will be intermittently energized, operating tomaintain closed the circuit of caution lamp 107. Magnet 103 being no longer energ1Zed,1t-s dash potcontrolle'd arma ture will fall and open the circuit of the clear lamp.- m

Under danger conditions, the veh cle Wlll IGCBlVGtIb recurring intervals one short 1mpulse followed by along impulse. These im-' pulses will operate wheel 85 throughtwo teeth and then release the wheel. When the wheel is operated through two teeth, projection 97 closes the circuit controller 100, and just before the wheel is released the following circuit is closed battery B, front contact 94:, conduc- I pulses received in a fixed interval of time;

The track is conductivelv continuous, as in the system illustrated in Fig. 1. p In the present system there is a motor stat-ionA, B, 0,1), etc.,-located at every third block. .-.t each otthese stationsthere is asingle phase motor 15 operating wheel 17 and shaft- 18, as

before. Fixed on shaft 18 are three disks 200,

201 and 202, each having short projections, or teeth, adapted to operate circuit controllers 203, 20 1 and 205, said circuit controllers be ing' connected respectively to conductors 206, 207 and 208 leading to one rail of the track at regularly spaced points a, Z), 0, (Z, etc, the stretchot track between adjacent connections being considered a block. One side of trans former 13 is connected to one of the contacts of the circuit controllers, while the other side 18 connected to the other track railrespective ly opposite the points of connection of con ductors20ti, 207 and 208.

At station A the teeth on each of disks 200. 201 and 202 are spaced 120, but any one tooth has a dilferent angular position from each ot the other teeth. The teeth at station ,C'are also displaced 120; on the three disks,

' at station It and controller 203 with the teeth on any one disk displaced with respect to those on the other two. At stations B and D the teeth on each of disks 2G0, 201 and 202 are separated byangle of 90, and all of the teeth at these respective stations are displaced with respect to each other. It will be understood therefore that the teeth atany one station are adapted to close the circuit controllers 203, 20d and 205 successively, no two teeth any one station closing the circuit controllers simultaneously.

Assuming that shaft 18 malres one revolution every four seconds, it will be clear that the vehicle shown will receive so tar station A is concerned, nine short impulses every four seconds, due to the successive operation of controllers 203, 20 i and 205 at this'station. It will also receive impulses tromt-he operation of the controllers at station B, but the operation of the controllers at station C will be ineffective, due to the impedance offered by the rails to the flow of alternating current, the frequency of the current being high enough to bring about this result.

Clear conditions obtain when there are at least three blocks in advance clear. Suppose there is a vehicle in the block between the points a and Z) and another vehicle in the block between the points (Z and e. Current impulses will be received by the rear vehicle from the operation of controllers 204C and 205 at station A and alsofrom the operation of controller 203 at station E. Due to the tact that the controllers at stations A and I3 are not synchronized, as in the system of 1, it is possible that one of the controllers 20% or 205 will be operated by a tooth at the same instant controller 203 is being operated at station I). If this snould be 'he case, it is clear that the rear vehicle would receive only eight short "mpulse's during the tour-second period. It is obvious'theretore that a. vehicle travelling under clear condi tions will receive at least eight short impulses every four seconds.

Considering caution conditions, suppose a vehicle is in the position shown on the draw ing' and an advance vehicle is in the block be tween the points 7) and c. In this case, the rear vehicl would receive current impulses tron] the operation of controllers 203 and 204 at station A. obviously, s mapulses every four s -conds. But suppose the rear vehicle is in the block between 5 and 0 and the advance vehicle is in the block between (Z and e. In this case the rear vehicle would receive impulses from the operation of controller 205 at station E. vt a tooth on disk at station synchronisn'i witl'i a tooth on disk 200 at station B, the rear vehicle would receive sir; impulses every four seconc s, before; but it there are two teeth at the stations operating the controllers 205 and 203 synchronously, the rear vehicle would receive only live imnot in pulses every four seconds. Under caution conditions therefore a vehicle will r ceive either five orsix impulses every four seconds Under danger conditions of course a vehicle will receive three impulses every four seconds.

To sum up; underclear conditions a vehicle will receive at least eight impulses every four seconds; under caution conditions, five or six impulses every four seconds; under danger conditions, three impulses every four seconds.

i arious mechanisms can be designed which will operate to give a clear indication on the vehicle when at least eight impulses are receivedevery four seconds; a caution indication when live to six: impulses are received; and a danger indication when three impulses are received. It may be pointed out here that the number of teeth on the disks, the angular velocity of shaft 18 and the angles between the teeth may be varied as desired, the figures given being merely by way of example.

As illustratedin the drawing, theselect-ive mechanism responsive to the number of im-. pulses received in a givenv time, comprises a shaft 215 driven at constant angular velocity by motor 216 of any suitable character; and the following; mec ranism controlled by the operation of said shal Fixed on the shaft are three wheels 217, 218 and 219, and rotatable on the shaft adjacent the respective wheels are toothed segments 220, 221 and 22' adapted be driven by pawls 223, 22a and 225, said pawls being operated respectively by magnets 226, 227 and Each of the segments has an arm rigid therewith carrying a pawl, or shoe, engaging the peripheries of wheels 217 etc., so that when the segments are operated by the pawls the arms are rotated upwardly, and in the intervals when the pa are not operated the arms move down with the wheels due to the engagement therewith of t 1e shoes.

Magnets 226, 227 and 228 are connected in parallel across conductors 230 and 231 which connect to front contac" of relay 31, whereby the magnets are simuit. icously energized upon the reception of each impulse. The pawls have different throws whereby they operate the segments thron dill'erent ungles on each operation lanl 223 has the smallest throw; pawl 22% has a somewl at larger throw; and pawl 225 has a still larger throw. T he speed of the motor and throw of pawl 228 is such that it e',, or more 11npulses are received every four seconds, segment 220 will be maintained in such position tha its arm will close the circuit, through clear lamp 283, but the nun'iber of pulses fall below this the arm of the se will rotate with wheel until stopped by pin 236, opening the ci cuit of the clear lamp. The throw of pawl such that the circuit of caution lamp will be closed solong as the frequency of the impulses does not fall below five per four seconds; and the throw of be received if the speed of the motor 216' I should fall belowits predetermined rate.

I provide, therefore, a centrifugal device 237- driven by shaft 215 adapted to open a circuit controller 238 in the common return of the signal circuits whenever the speed of the pawl 305, and the latter in its disengagingv -motor drops below its predetermined speed of operation.

Fig. 3 illustrates a modified form of appas ratus adapted for use with. a track system such as shown by Fig. 2. This system includes a constant speed mot-or 300 driving a shaft 301 on which is flXGQl'fl-D arm 302 sweeping over cont-act segments 303 during agreater part of its revolution; andan' impulse mech anism including a toothed segment 304 operated by a pawl 305 and held in'o-perate-d positions by adog 306. Pawl 305 is operated by a magnet 307 and dog 306 is operated by a magnet 308. Dog 306 is held in engagementwith the teeth of segment 304 when magnet 308 is energized, and is released by a spring 309 when the magnet is deenergized. When dog 306 is released it also disengages driving movement closes a circuit controller 310.

' With the assumptions made with respect to' centrifugal device, 318 operating a circuit.

controller 319 assures that motor-"300 willoperate at a predetermmedspeed. Contacts 312, 313 and 314 are in the clrcuits respectively of stick relays 320, 321 and 322, these re-' lays controlling magnets 323,324 and 325, the latter, in turn, controlling clear, caution and danger lamps 326, 327 and 328, respectively.

the'system of Fig. 2, it may beassumed that the time during which the contact segments 303 are bridged is four seconds per revolution of arm 302. "When these segments are .bridged'the circuit of magnet 308 is closed,

' engaged with the teeth of segment 304.

as will be obvious from the drawing, and the driving pawl 305 and holding pawl 306' are the mechanism is conditioned for operating segment 304 for a period of four seconds at recurring intervals.

It will be recalled that at least eight impulses are received under clear conditions every four seconds; five to 81X under caution conditions; and three under danger conditions. If, therefore, the vehicle is travelling under clear conditions, magnet 307 will re ceive at'leas't eight impulses from battery B during the four second interval 1n which seg- Thus ments 303 are bridged, the circuit of magnet 307 being closed when relay 31 is energized, as will be obvious from the drawing. These eight or more impulses will operateto step segment 304 through eight steps, the segment having only eight teeth so that it cannot be stepped further. lVhen the segment is stepped through eight steps, arm 311 engages contact 312, so that when arm 302 passes out of engagement with contactsegme'nts 303, dog 306 and pawl 305 are released from thesegment closing. the following circuit: battery B, conductor 330, controller 319, conductors 331, 332:,and. 303, contacts 310, conductor 334, arm 311, contact 312, conductor 335, stick relay 320, conductors 336 and 337,v contacts 317, and back to battery through conductors 338 and 339. Relay 320 is energized only for an instant but sufliciently to cause it to pick up. Relay 320 is held energized, however, until arm 311 reaches its initial position, by means of the following stick circuit: battery B, conductor 330, controller 319, conductors 331, 332,340 and 341, front contact of relay 320, the relay winding, conductors 336 and 337 contacts 317 and back to battery through conductors 338 and 339. As said arm 311 approaches its initial position and just before it opens the stick circuit, closes at contacts 316 the following, circuit: battery 13, conductors 339 and 338, contacts 316, conductor 343, front contact 344 ofrelay 320, 0011-.

ductor 345, magnet 323, conductors 346, 340, 332 and 331, c0ntroller 319 and conductor 330. f

If the vehicle is travelling under caution conditions, segment 304 will be operated through airangle of either five or six teeth during the four second interval in which the contact segments 303 are bridged. In either case arm 311will engage contact 313, this contact being long enough for that purpose. Hence at the end of the four second interval,

when arm 302 asses out of en a ement with segments 303, releasing the driving and holding pawls, a circuit is closed through stick relay 321 by way of conductor 345, this circuit being the same as that traced for relay 320 except that in place of conductor 335 it includesconductor 345. The stick circuit of relay 321 is also the same as that traced for relay 320 except that in place of conductor 341 it has the conductor 346. hen now arm 311 approaches its initial position, it closes at contact 316 the circuit of magnet 324 through front contact 347 of relay 321.

' If the vehicle is travelling under danger conditions, segment 304 will be operated through an angle of three teeth during the four-second interval in which the contact seg ments 303 are bridged. When operated through'this angle arm 311 will engage contact 314, and when the segment is released a pick-up circuit is closed throughrclay 322 by way of conductor 350. This relay has a stick circuit including conductor 85h saidcircuit being-otherwise the same as described i'or relay 320. Then the arm returns to initial position the circuit of magnet 325 is closed at contacts 316 and then the stick circuit of relay 322 is broken at contacts 317.

From the above it will be understood that under clear conditions, magnet 323 is intermittently energized, once every four seconds, and when so energized maintains closed the circuit of clear lamp 326; that under caution conditions magnet 324 is intermittently eners giz'ed,.maintaining closed the circuit of cantion lamp 327; and that under danger conditions magnet 325 is intermittently energized closing circuit oi the danger lamp 828.

The invention is susceptible of embodiment in other forms than those described, and I do not intend to limit the scope thereof except as defined by the claims.

I claim:

1. A railway signalling system including a stretch oi track the rails oi which are con ductively continuous throughout, means for impressing impulses of alternating energy across the track rails at a'plurality of spaced points, said means operating to impress i1n pulses at said points asynchronously, a vehicle having a translating device responsive to the impulses, and governing means controlled by the translating device adapted to give ditierent indications according to the number o't impulses transmitted in a fixed time.

2. A railway signalling system including a stretch of track the rails of which are conductively continuous throughout, means for impressing impulses of alternating energy across the track rails at a plurality of spaced points asynchronously, a vehicle having a translating device responsive to said impulses, step-by-step mechanism controlled by the translating device, and control mechanism variably affected according to the extent of movement of said mechanism within a given fixed time.

3. A railway signalling system including a. stretch of track the rails o't' which are conductively continuous throughout, means for impressing impulses of alternating energy across the rails at a plurality of spaced points asynchronously, a vehicle travelling on the track having a translating device responsive to the impulses, impulse mechanism controlled by the translating device, train control devices governed by the impulse mechanism, a timing device and means operated thereby for rendering the impulse mechanism operative during regularly recurring periods of time.

4:. A railway signalling system including in combination means for impressing impulses of alternating energy across the track rails at a plurality of spaced points asynchronously, a vehicle having a translating device responsive to the impulses whereby the trans lating device will be variably ali'ected according to the number of points in advance of the vehicle from which energy is transinitted asynchronously and governing means controlled by the translating device adapted to give diil'erent indications according to the number of separate impulses transmitted in a given time. c

5. A railway signalling system including in combination means for impressing impulses of electrical energy across the track rails at extent of movement oi said mechanism with in a given iiXed time.

6. 1 railway signalling system including in combination means for connecting electrical energy across the track rails at a plurality of spaced points asynchronously with substantial intervals between theconnections and train control devices including impulse mechanism responsive to said energy adapted to give diiierent indications according to the number of points in advance from which energy is transmitted theretoasynchronously.

7. A railwaysignalling system includinga stretch of track, means i 01 connecting sources o-telectrical energy across the track rails atv a plurality of spaced points asynchronously with substantial time intervals between the successive connections, whereby impulses are received by a vehicle at any point on the track according to the number of points in advance from which energy is transmitted, a vehicle having a translating device responsive to the impulses and train control mechanism governed by said translating device.

8. In a railway signalling system, means for connecting electrical energy acrossthe track rails at a plurality of spaced points asynchronously,said means including constantly operating motors and circuit controllers operated thereby, eachcircuit controller operating at all times independently of the other circuit controllers, and a vehicle having train control mechanism including a translating device responsiveto said energy adapted to give different indications according to the number of points in advance from which energy istransmitted thereto asynchronously.

9. A railway signalling system including a stretch of track, means for connecting electricalenergy across the track rails at a plurality oi spaced points asynchronously, said means including constantly operating motors at said points and circuit controllers oper-' ated thereby, said circuit controllers being the number of impulses interval. a v

non-adjustable with respect to eachother,

and a vehicle having train control mechanism including a translating dev1ce responsive to said energy adapted to give dififerent lndicationsjaccording to the number of points in advance or" the vehicle from which energy is transmitted-thereto asynchronously.

10. A railway trailic controlling systemineluding in combination, means at spaced points along the track for causing asynchronous electrical impulses in the track rails, a vehicle having means for integrating the im pulses per fixed interval of time, and train control devices governed by said integrating means adapted to give difierent indications a-ccording'to the number of impulses received during said interval.

11; A railway trafiic controlling system including in combination, switches at spaced points along the track adapted to close electrical connections across the track rails and thereby cause electrical impulses in said rails,-

means for closing said switches asynchronously and periodically, a vehicle having means for integrating the impulses per fixed interval, and signals governed by said int-egrating means selectively'in accordance with received during said i 12; A railway traflic controlling system in eluding in combination, a conductivelycontinuous stretch of track, switches at spaced points along the track for closing electrical connections across the track rails and thereby causing'electrical lmpulses to flow in the track rails, means for closing said switches asynchronously and periodically, a vehicle having means for integrating the impulses per fixed interval, and train control devices governed by said integrating means.

13. In a railway traflic controlling system,

car carried apparatus adapted to cooperate with a track system having'means to cause impulses of a certain frequency to flow in the track rails, comprisinga coil disposed in in ducti-ve relation to the rails, a translating device connected to said coil,'impulse counting ineanscontrolled by said device,-means operating independently of the impulses for renderingsaid counting means operatively effective at recurringintervals, and train control mechanism governed by said counting means selectively according'to the number of impulses received while said counting means is rendered operatively effective.

counting means operatively effective periodically'during a definiteinterval of time, and train control mechanism governed by said impulseco'unting means selectively according to the number of impulses received during said interval a i In testimony whereof I hereunto afiix my signature.

EDWARD o. SASNETT. 

